Cohort participation and retention
Timeline of surveys since 1996
| Cohort | 1989-95 | 1973-78 | 1946-51 | 1921-26 | |
|---|---|---|---|---|---|
| Survey 1 | Year (age range) | 2013 (18-23) | 1996 (18-23) | 1996 (45-50) | 1996 (70-75) |
| Respondents (N) | 17010 | 14247 | 13714 | 12432 | |
| Survey 2 | Year (age range) | 2014 (19-24) | 2000 (22-27) | 1998 (47-52) | 1999 (73-78) |
| Respondents (N) | 11344 | 9688 | 12338 | 10434 | |
| Survey 3 | Year (age range) | 2015 (20-25) | 2003 (25-30) | 2001 (50-55) | 2002 (76-81) |
| Respondents (N) | 8961 | 9081 | 11226 | 8646 | |
| Survey 4 | Year (age range) | 2016 (21-26) | 2006 (28-33) | 2004 (53-58) | 2005 (79-84) |
| Respondents (N) | 9007 | 9145 | 10905 | 7158 | |
| Survey 5 | Year (age range) | 2017 (22-27) | 2009 (31-36) | 2007 (56-61) | 2008 (82-87) |
| Respondents (N) | 8495 | 8199 | 10638 | 5560 | |
| Survey 6 | Year (age range) | 2019 (24-29) | 2012 (34-39) | 2010 (59-64) | 2011 (85-90) |
| Respondents (N) | 8346 | 8009 | 10011 | 4055 | |
| Survey 7 | Year (age range) | 2023 (28-33) | 2015 (37-42) | 2013 (62-67) | Surveyed at six monthly intervals from November 2011 (see next table) |
| Respondents (N) | in progress | 7186 | 9151 | ||
| Survey 8 | Year (age range) | 2018 (40-45) | 2016 (65-70) | ||
| Respondents (N) | 7121 | 8622 | |||
| Survey 9 | Year (age range) | 2021 (43-49*) | 2019 (68-73) | ||
| Respondents (N) | 6875 | 7956 |
Data known as at 20th April 2023.
*This is more than the usual 5 year age range because the survey was open for 17 months due to COVID-19.
1921-26 Cohort: number of respondents for each six-monthly follow up (6MF)
| Survey | Total (N) | Year submitted: | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Age range (years): | 85-90 | 86-91 | 87-92 | 88-93 | 89-94 | 90-95 | 91-96 | 92-98 | 93-99 | 94-100 | 95-101 | 96-102 | 97-103 | ||
| 6MF1 | 3855 | 2829 | 945 | 59 | 13 | 2 | 4 | 1 | 2 | 0 | 0 | 0 | 0 | 0 | |
| 6MF2 | 3395 | 3069 | 248 | 45 | 14 | 8 | 1 | 5 | 3 | 1 | 1 | 0 | 0 | ||
| 6MF3 | 2993 | 1651 | 1178 | 96 | 33 | 16 | 8 | 6 | 4 | 1 | 0 | 0 | 0 | ||
| 6MF4 | 2623 | 2216 | 292 | 57 | 27 | 8 | 12 | 5 | 4 | 2 | 0 | 0 | |||
| 6MF5 | 2311 | 921 | 1169 | 133 | 41 | 16 | 13 | 7 | 7 | 3 | 1 | 0 | |||
| 6MF6 | 2032 | 1591 | 299 | 64 | 33 | 18 | 11 | 8 | 5 | 3 | 0 | ||||
| 6MF7 | 1780 | 595 | 985 | 110 | 35 | 29 | 8 | 9 | 6 | 3 | 0 | ||||
| 6MF8 | 1556 | 1129 | 311 | 52 | 28 | 17 | 9 | 7 | 3 | 0 | |||||
| 6MF9 | 1376 | 439 | 737 | 133 | 33 | 14 | 9 | 6 | 5 | 0 | |||||
| 6MF10 | 1215 | 823 | 285 | 55 | 23 | 17 | 7 | 5 | 0 | ||||||
| 6MF11 | 1064 | 260 | 612 | 124 | 44 | 15 | 5 | 2 | 2 | ||||||
| 6MF12 | 911 | 569 | 252 | 54 | 22 | 8 | 6 | 0 | |||||||
| 6MF13 | 778 | 160 | 477 | 96 | 23 | 19 | 3 | 0 | |||||||
| 6MF14 | 673 | 413 | 194 | 38 | 17 | 10 | 1 | ||||||||
| 6MF15 | 555 | 116 | 329 | 71 | 24 | 13 | 2 | ||||||||
| 6MF16 | 461 | 274 | 139 | 34 | 12 | 2 | |||||||||
| 6MF17 | 374 | 79 | 224 | 51 | 15 | 5 | |||||||||
| 6MF18 | 304 | 170 | 103 | 27 | 4 | ||||||||||
| 6MF19 | 242 | 43 | 155 | 43 | 1 | ||||||||||
| 6MF20 | 192 | 110 | 69 | 13 | |||||||||||
| 6MF21 | 137 | 26 | 91 | 20 | |||||||||||
| 6MF22 | 85 | 56 | 29 | ||||||||||||
| 6MF23 | 30 | 8 | 22 |
This six monthly survey has no finish date and therefore we continue to receive surveys for each wave.
Each row shows the total number of respondents, followed by the number of responses made each year, for each individual wave.